In terms of prosecuting Blackwater 'contractors' for shooting civilians,
The legal path will not be easy, but there are options. The government could seek to prosecute the guards under the Military Extraterritorial Jurisdiction Act, or MEJA, which extends American criminal law to contractors overseas. Or it could try to court-martial the guards under the Uniform Code of Military Justice, which was amended last year to cover contractors accompanying the armed forces in the field.When you follow the law, especially if as the occupying power you made the law incredibly self-serving, things get so complicated. If the shoe were on the other foot, this would be easy - Bush would call them "illegal combatants", and argue that no further law or due process was required.
It could also offer a plea deal — including some prison time — to any guards found to have recklessly violated deadly force rules. The guards may be a lot more interested if Washington makes it clear that it is ready to waive the immunity from Iraqi prosecution, granted to contractors by the American occupation government three years ago.
None of these options is foolproof. MEJA applies to contractors that accompany American armed forces, while the Blackwater guards were working for the State Department. Using the military code would face the same problem and would have to contend with Supreme Court opinions from the 1950s and 1960s barring the courts-martial of civilians.